Cisco Aironet 350 is quite good pcmcia wi-fi card well supported in linux. It's only flaw is the absence of external connector, which can be easily resolved.

My initial inspiration was an article by VK1EME,
but I dare to say that my approach is more elegant and in the end more practical and prettier.

What is needed? Soldering iron (not the one using transformer, if possible, although I have forgot about it once and the card survived), solder, flux, pliers, knife, epoxy glue, female RSMA connector for 3mm cable (the chaos in R/SMA connectors is explained in depth here) - sold e.g. here, 3 mm wi-fi cable - just a few centimetres, glue and clothes pegs.

First you need to strip the plastic cover, it goes easily, just stick a knife below it and lever.

The thing next to the diodes is a U.FL connector. It's disadvantage is cost, is difficult to get and one can use it only 30 times. Perhaps it would be be better to remove it and plug the external connector instead of it, but VK1EME didn't and I didn't want to risk; it works ok, so why bother?

Use a knife (the kind that is used for cutting cardboard) to make space for further operation. Next time I would leave more plastic at the left to ease glueing the cover back.

The golden rectangle is the inner antenna. It is necessary to cut off its connection with the inner card electronics, 1mm space should be enough, but the more the better. The leads need to be sand-papered for better soldering, but be careful - the metal dust shouldn't get inside.

Tag the connector on to the cable in the usual way - solder the middle pin, put it through, put the tube around the shielding and press with pliers to make it (a bit) flat.

Cut the other end of the cable right near the connector, strip the insulation and the middle part and divide the shielding into two "plaits", if possible on a level with the connector.

Then (carefully) solder the connector so that its widest part was at in the edge of the card. The middle wire to the middle lead, shielding to the border ones. (Not sure if it's necessary, but to be sure I covered the inner antenna with a tape.)

Then seal the connector on all sides with the epoxy glue and let it dry.

The original plastic cover needs adjustation - cut out where the connector is. Then use some glue, fix it with the pegs and let dry.